Process of subjecting wood and similar materials to a preliminary treatment for the manufacture of paper, board, etc.



7 and to employ for this purpose the usual Patented Aug. 31, 1926.-

UNITED STATES PATENT OFFICE.

HUBEBT IBRKUNLIOH, OF FREIWALDA'U, CZECHOSLO'VAKIA.

rnoonss or sumnorme woon AND SIMILAR Marni-trans To A PRELIMINARY TREAT- MENT FOR THE manuraorunn or PAPER, Bormnn'ro;

pose of softening the fibres. The strength of papers produced from wood treated-in the manner indicated is not veryv great while" it has been found impossible to .dye such papers which usually show a dark color in? I am aware that processes lighter shades. are known to boil the wood in vacuumiin order to prevent the dark color of the paper chemicals. The application of this process will undoubtedly facilitate dyeing, but the strength of the paper produced thereby -re-.

mains unsatisfactory while, in addition, this process is, as a rule, very cumbersome and expensive.

The present invention eliminates these drawbacks by dividing the steaming or boiling process into several successive steps or phases by altering the steam pressure and by subjecting the wood, etc., to a prolonged '1 water treatment with or without the addition of chemicals or with and without pres sure.

The steaming or boilin process according to the present invention 1s, for example, divided into four phases. The first phase operates with increasing steam pressure to a pressure of 2-4 atmospheres above atmosphere whereby a gradual warming of the wood in a boiler of known design is effected. During the second phase the steam pressure remains approximately stationary for about 2-4 hours while a certain amount of drying and a partial gasifieation of the volatile particles of the wood takes lace. This partial gasification continues or a while dur ing the third phase, whereupon the boiler pressure is gradually reduced to atmospheric within 3-8 hours so as to cause par- :;intende d.

"suit the requirement wood or prepare it quality to be T e-ford f is phases mentione O may' be "altered t innd of. or he manufaeturesof 05 i1' the fourth and ss lways consists in ood with water tain chemicals.

special kinds of ap final phase of the thoroughlyw saturati which-may or may I claim: The -process of subjecting wood and similar materials to a preliminary treatment in the manufacture-- of'paper, board or equivalent products consisting in" dividing the steaming processfinto four successive and separate steps, t-he firststep comprising a slow preparatory heating of the material to be treated up to a; pressure of 2-4 atmos pheres above atmospheric, according to the roduced, while, during. the second step, this pressure is kept approximately constant for about 2-4 hours and, during the third step, gradually reduced to atmospheric within 38 hours by regulating the steam supply; the fourth step consisting in the admission of water to the boiler, with or without an admixture of chemicals, for the purpose of subjecting the material to constant saturation for a period of 4, 5 or more hours, while the first three stepscan M HUBERT B AU LICH. 

